An important characteristic that Hemichordates share with Chordates is:

1. Ventral tubular nerve cord

2. Pharynx with gill slits

3. Pharynx without gill slits

4. Absence of notochord

Which among these is the correct combination of aquatic mammals?

1. Dolphin, Seals, Trygon

2. Whales, Dolphin, Seals

3. Trygon, Whales, Seals

4. Seals, Dolphin, Sharks

Choose the correct statement.
1. All mammals are viviparous
2. All cyclostomes do not possess jaws and paired fins
3. All reptiles have a three-chambered heart
4. All Pisces have gills covered by an operculum

In the case of Poriferans, the spongocoel is lined with flagellated cells called:

1. Oscula

2. Choanocytes

3. Mesenchymal cells

4. Ostia

A jawless fish, which lays eggs in freshwater and whose ammocoetes larvae after metamorphosis return to the ocean is?
1. Eptratretus
2. Myxine
3. Neomyxine
4. Petromyzon

Metagenesis refers to?